Tower blocks have been left vulnerable to rapidly spreading fires by years of deregulation and the fashion for cladding their exteriors, experts said yesterday.

Basic concrete high-rises in Britain have never experienced a serious spreading fire. The first disaster happened on a building that had had exterior renovation work (cladding), that allowed flames to spread.

Miles Glendinning, a historian of architecture and housing, said that postwar tower blocks quickly earned a reputation for fire safety. That risked being lost with the popularity of cladding, which was introduced to brighten surfaces and improve energy conservation.

“The basic structure of concrete blocks should be fire resistant,” Professor Glendinning said. “There have been hundreds of fires in tower blocks which have been contained in the flat.”